Magneto-optical properties of wider gap II-VI ZnMnTe and ZnMnCoTe films

In CdMnTe and CdMnCoTe films, Mn shifts the absorption edge toward higher energies. However, this gap shift occurs at around 2.1 eV because the band gap of the combination of CdTe (1.53 eV) and wideband gap MnTe (2.9 eV) is small. In order to widen the gap of A^II_1-xMn_xB^VI alloys and effectively use LDs that work at shorter wavelengths for Faraday rotation, we have studied ZnMnTe and ZnMnCoTe films, whose parent materials are wideband gap ZnTe (2.28 eV) and MnTe. The relationship between the quantity (αhν)² and the optical energy for Cd_0.65Mn_0.35Te and data on Zn_0.75Mn_0.25Te and Zn_0.79Mn_0.20Co_0.01Te films showed that the direct gap energy of the Cd_0.65Mn_0.35Te film is roughly 2.25 eV and the gap of Zn_0.75Mn_0.25Te and Zn_0.79Mn_0.20Co_0.01Te (∼2.4 eV) is 0.15 eV (∼40 nm) larger than that of Cd_0.65Mn_0.35Te. The increas- e is due to the combination of wideband gap ZnTe and MnTe. Transparency and Faraday rotation are observed for Zn_1-xMn_xTe and Zn_1-x-yMn_xCo_yTe films.